U.S. Pat. No. 522,545 issued in 1894 to I.D. Wright shows a device for inverting the movement of an oar. More particularly, the oar comprises two distinct oar sections which radially engage respective tangentially adjacent cylindrical sockets pivoted onto a swivelled support member. The sockets are linked to each other by means of a pair of wires each attached at its first end to a first socket and at its second end to a second socket, although on the opposite side relative to the first socket, with each wire crossing the other wire between the two tangentially adjacent cylindrical socket walls. Thus, upon pivoting the handle oar section rearwardly, the paddle oar section is also pivoted rearwardly, for forwardly propelling the watercraft in the water. A person may thus sit in the watercraft while facing the bow of the watercraft when rowing, and still benefit from the full strength of a rearwards shoulder and arm motion to pivot the oars for frontwardly propelling the watercraft.
U.S. Pat. No. 3,884,175 issued in 1975 to G.D. Bellis shows another device for inverting the movement of an oar. This device is similar to the above-mentioned Wright device, although it includes interconnected geared sockets instead of the wire-interconnection detailed hereinabove. The Bellis patent further shows a swivel mount for allowing the oar inverting device to be swivelled onto the watercraft, for allowing pivotal movement of the oars in a vertical plane; this vertical pivotal movement of the oar is necessary, to allow the user of the watercraft to alternately take the oars out of the water during the forward paddle stroke, and into the water during the rearward propelling paddle stroke. As can be seen in the Bellis patent, the swivel mount simply comprises coextensive ears engaging a complementary slot in a bracket fixed to the watercraft, which allows the oars to pivot in a vertical plane.
The problem associated with the above-described Wright and Bellis patents is that the oar inverting device is not attached to the watercraft hull securely, nor in a manner which allows versatile displacement of the oars. For example, in the Bellis patent, the swivel mount could be accidentally released from the upwardly open slot in which it rests.
U.S. Pat. No. 4,411,214 issued in 1983 to K. Horiuchi shows that it is known to provide inner reinforcement tubes (reference number 8 in FIG. 3 of the Horiuchi patent), that are located inside the watercraft hull and attached on the inner face thereof, with the oar outriggers (reference number 6 in the Horiuchi patent) being attached on the opposite outer face of the hull, in register with the inner tubes. The inner tubes, however, require complex installation techniques, especially if rotomoulding techniques are used to mould the watercraft hull. Moreover, the attachment of the outriggers to the hull will cause important stresses to be induced into the proximate hull wall, which may result in fissuring and breakage of the hull wall with concurrent accidental release of the outrigger attachment from the hull.
U.S. Pat. No. 4,623,314 issued in 1986 to G.B. Waugh shows that it is known to provide single outrigger arms to pivotally support the oars at an intermediate portion thereof, away from the hull side edges.